The grand opening of Sean Adler’s Simi Valley coffeehouse, Rivalry Roasters, had taken place less than three weeks earlier. Tucked into a strip mall, the small shop was a dream of Adler’s, one he worked tirelessly to pursue after a heart attack kept him from a future as a sheriff’s deputy.

But on Thursday, bouquets of flowers lined the outside doors of the coffee shop, as patrons and friends came to say goodbye. The night before, Adler, 48, was one of the 12 people killed by a gunman in the mass shooting at Borderline Bar & Grill in Thousand Oaks, where he worked as a bouncer and security guard.

He’d kept that job – and another bouncer job at nearby Azar’s Sports Bar – to support his two family while the coffee shop got off the ground. On the day of the shop’s opening, his two sons, ages 17 and 12, were by his side, making coffee and running the register.

Often, he would leave the shop and head straight to one of his other jobs to work the night shift. His sister, Valerie Adler, told NBC News that on Wednesday night, as a gunman opened fire on the crowded bar, Adler attempted to disarm him. To those who knew him best, that bravery came as no surprise.

“It’s absolutely the kind of thing he would do,” said Danny Evans, a childhood friend. “He just loved people.”

“He gave his all, to whatever it was he did,” added Mike Nolan, a friend whom Adler met through the Simi Valley Chamber of Commerce. “He worked his butt off. He did everything he could to make this shop a reality.”

For years, he bounced around between careers, serving, at various times, as a salesman, a strength and conditioning coach for Royal High School, and a youth soccer coach. He’d hoped to eventually become a police officer and was training with the Los Angeles County Sheriff’s Department when a 2017 heart attack changed his plans.

That year, Adler also lost his father. But amid the tumult, friends remember Adler as unrelentingly positive with an infectious sort of charisma.

“He was always smiling,” said David Weinstein, who’d been friends with Adler since they were children. “Even when things were crashing around him, he still managed to stay upbeat.”

With Rivalry Roasters, Adler had found his niche. In the hours before a candlelight vigil was held on Thursday night, patrons and friends stopped by the coffee shop to pay their respects.

Some left notes to say goodbye. “To our favorite coffee guy, you will be missed dearly,” one read.

“These flowers,” another read, “are nowhere near as vibrant as you.”

A vigil for Adler will also be held on Friday night at Rivalry Roasters.

Ryan Kartje is a sports features reporter, with a special focus on the NFL and college sports. He has worked for the Orange County Register since 2012, when he was hired as UCLA beat writer. His enterprise work on the rise and fall of the daily fantasy sports industry (http://www.ocregister.com/articles/industry-689093-fantasy-daily.html) was honored in 2015 with an Associated Press Sports Editors’ enterprise award in the highest circulation category. His writing has also been honored by the Football Writers Association of America and the U.S. Basketball Writers Association. A graduate of the University of Michigan, Ryan worked for the Bloomington (Ind.) Herald-Times and Fox Sports Wisconsin, before moving out west to live by the beach and eat copious amounts of burritos.